Addition polymer composition containing isoxazolidine compounds

Abstract

A resin composition is provided containing a resin (preferably a thermoplastic resin) and an isoxazolidine. The composition exhibits enhanced melt stability and color stability. The composition is useful for making thermoplastic articles such as extruded sheet and film. Preferably the thermoplastic resin is a polyolefin such as polypropylene. A method for stabilizing thermoplastic polymers is also provided.

I claim: 
     
       1. A thermoplastic resin composition comprising: (a) a thermoplastic resin,   (b) an isoxazolidine in an amount effective to enhance the melt stability of the thermoplastic resin; wherein said isoxazolidine is selected from isoxazolidine represented by the general formula: ##STR5## wherein each R1, R2, R3, R4, R5, R6 and R7 is independently selected from hydrogen, alkyl, aryl, alkylaryl and aralkyl.   
     
     
       2. The composition of claim 1 wherein said isoxazolidine is present at a level of between 0.005 and 2.0 percent by weight based on the total weight of the composition. 
     
     
       3. The composition of claim 1 wherein said thermoplastic resin is present at a level of at least 90 percent by weight based on the total weight of the composition. 
     
     
       4. The composition of claim 3 wherein said thermoplastic resin is a polyolefin. 
     
     
       5. The composition of claim 4 wherein said thermoplastic resin is polypropylene. 
     
     
       6. The thermoplastic composition of claim 5 wherein said composition consists essentially of said thermoplastic resin and said isoxazolidine. 
     
     
       7. The thermoplastic composition of claim 1 wherein R3, R4 and R5 of said isoxazolidine are each hydrogen and each R1, R2, R6, and R7 is independently selected from hydrogen, alkyl, aryl, alkylaryl and aralkyl. 
     
     
       8. The composition of claim 7 wherein said isoxazolidine is 2,3,5-triphyenylisoxazolidine. 
     
     
       9. The composition of claim 7 wherein said isoxazolidine is 2,3,5,5-tetraphenyl isoxazolidine. 
     
     
       10. The composition of claim 1 further comprising a metal salt of a fatty acid. 
     
     
       11. The composition of claim 1 further comprising calcium stearate. 
     
     
       12. The composition of claim 1 further comprising a phosphite. 
     
     
       13. The composition of claim 1 further comprising a neutralizer and a phosphite. 
     
     
       14. A thermoplastic resin composition comprising: (a) a thermoplastic resin,   (b) an isoxazolidine in an amount effective to enhance the melt stability of the thermoplastic resin; wherein said isoxazolidine is selected from isoxazolide represented by the general formula: ##STR6## wherein each R 1 , R 2 , R 3 , R 4 , R 5 , R 6  and R 7  is independently selected from hydrogen, alkyl, aryl, cycloalkyl of 5 to 12 carbon atoms, alkylaryl, aralkyl, a straight or branched chain alkyl of 1 to 18 carbon atoms terminated by a group selected from --OR', NR' 2 , --SR', --COOR' and --CONR' 2 , and a straight or branched chain alkyl of 1 to 18 carbon atoms interrupted by a group selected from arylene of 6 to 10 carbon atoms, --O--, --S--, --SO--, --SO 2  --, --COO--, --OCO--, --CONR'--, --NR'CO-- and --NR'--; and wherein each R' is independently hydrogen, alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, or alkenyl of 3 to 6 carbon atoms.   
     
     
       15. A method for melt stabilizing a thermoplastic resin, said method comprising: admixing a thermoplastic resin and a melt stabilizing amount of an isoxazolidine wherein said isoxazolidine is selected from isoxazolidine represented by the general formula: ##STR7## wherein each R1, R2, R3, R4, R5, R6 and R7 is independently selected from hydrogen, alkyl, aryl, alkylaryl and aralkyl. 
     
     
       16. The method of claim 15 wherein said isoxazolidine is 2,3,5-triphenylisoxazolidine.